Inflatable airbags are hidden in non-visible areas of modern vehicles, where they wait to perform their safety function in the event of a collision. When a collision is detected, these devices inflate in a fraction of a second, suddenly protruding from their hiding spots and into the passenger cabin to help prevent vehicle occupants from colliding with more rigid and thus more dangerous parts of the vehicle, such as the windshield, steering wheel, door frame, etc. When the uninflated airbag is concealed behind a vehicle interior panel, at least part of the panel must be quickly moved away to make room for the inflating airbag when it is deployed. In some cases, a deployment opening is formed through the panel by the airbag itself, which applies a large amount of force in a short period of time to the concealing panel. Airbag tear seams have been developed to allow vehicle designers to precisely locate such deployment openings. Efforts have been made to make airbag tear seams invisible to vehicle occupants to provide a passenger cabin environment that is more aesthetically pleasing and less utilitarian in appearance.
U.S. Pat. No. 7,976,764 to Schlemmer et al. discloses a technique for locally weakening a multi-layered composite trim piece for an automotive vehicle material so the trim piece predictably tears along the locally weakened section upon airbag deployment or in the event of a crash. The technique includes forming blind holes in the trim piece from the back side so that the weakened section is not necessarily visible from the front side. The technique relies on the holes being formed in the trim piece only after the multiple layers are assembled together as a single component and also requires multiple different laser powers—i.e., a relatively high-wattage laser forms part of the holes in one layer, and a relatively low-wattage laser forms part of the holes in other layers.